Using disk analyzer, I deleted "media" because it was taking up most of my hd. Apparently that disabled the function of automatically detecting my external data sources, i.e. ext hd or flash drive.
How can I recover from that?
When I plug in my flash drive the system says: "Cannot mount drive"

Ubuntu uses /media as its common mount point for external media and network shares. Without it, Ubuntu doesn't know where to mount your external media. You need to put it back:

sudo mkdir /media
sudo chmod 755 /media

I'm curious to know why you thought /media was taking up most of your hard drive. It shouldn't be doing that. It sounds to me like your disk analyzer was reporting how much space was being taken on devices mounted to /media, not necessarily being taken up by your local drive. If anything in /media is taking up actual space on your local drive, then something is wrong.

Yes, I figured out after it was too late that, apparently, it was taking
into account my ext hd which has over 200 mb of occupied space. (The hd
on my acer computer is only 320) The reason I thought there was a
problem was that I was trying to download a fairly large file and the
system told me that I didn't have room.
As you can probably tell, I am a complete novice re linux.
Can you walk me thru the terminal process?
[root@localhost ~]# is what I see when I go to terminal.
Help!
Thanks,
Walker

Well, first off, I highly recommend, for security purposes, you stop logging
in as root. When you run apps as root, you are offering them unlimited
access to your system, which can be problematic. Create a user account and
use sudo whenever you need to use commands as root. I know you are logged
in as root, because...

root@localhost
^^^^ ^^^^^^^^^^
user host name

I am afraid, in my opinion that use of the terminal is probably a little too
broad a subject to cover by email. It would be better to have say what you
are trying to do and ask how to do it from the command line.

Putting back the directory you removed is easy. I gave the terminal commands to do that, but I'll explain them:

sudo mkdir /media

That command creates, or makes, a directory named media, and places it in your root directory, or /

Your root directory is, just like it sounds, the very first directory on your drive. All other files and directories branch off of this one.

sudo tells the terminal to execute your command as if you were the root user (the use of "root" here is different from the use of "root" with respect to directories. "root" with respect to users means it is the primary user, which is also granted complete administrator rights to the machine. That is why, as Sean mentioned, you should never log in as root unless you really, really have to (and 99.99% of the time, you don't). sudo grants administrator privileges on an as-needed basis, which expires soon after the command is executed. Of course, the account you ARE using must have permission to use sudo.

With Ubuntu, when you run the installer, you are asked to create the first account. Ubuntu grants this account limited admin privileges, including the use of sudo. Also with Ubuntu, the ability to log in locally as root is disabled by default, so that has me a bit curious as to how you are logged in as root.

But, anyways...

sudo chmod 755 /media

This command, again using sudo, changes the access permissions, using the chmod command, of your newly-created directory, /media. The 755 designates the permissions. If you ever look at a file directory in terminal using the ls -l command, you will see a whole lot of characters that look something like this:

drwxrwxrwx 1 owner group

These are the permissions for three distinct groups: The owner, those in the owner's group, and those not in the group. The first set of "rwx" indicates "read", "write", and "execute" permissions, respectively, for the owner. The second set indicates the permissions for those in the same group as the file or directory belongs to, while the third set are the permissions for those people not in that group. When you run the chmod command, the three digit number sets all the permissions for that folder all at once. The first digit, 7, grants read, write, and execute permissions for the owner; the second digit, 5, grants read and execute permissions, but not write, for the group; and the third digit, 5, grants read and execute permissions, but not write, for everyone else.

I suggest you use Linux mint gnome and I recommend mandriva .
Mandriva has a free version and a stick version .

Using disk analyzer, I deleted "media" because it was taking up most of my hd. Apparently that disabled the function of automatically detecting my external data sources, i.e. ext hd or flash drive.
How can I recover from that?
When I plug in my flash drive the system says: "Cannot mount drive"

Did I miss something? Did the user say that he or she wanted to start over
and reinstall or express unhappiness with their distribution?

These kinds of suggestions are not helpful IMO. They are just a superficial
promotion of one distro over another. They do not promote Linux in general
or increase understanding and show no appreciation of the problem or pose a
solution. Are you suggesting that you cannot delete a root folder in Mint or
Mandriva? This is cherry picking.

Walker Moran:
Absolutely. For security reasons, one should always log in as User. A good practice would be to log in as Root only when doing updates or any other needed mods. I don't think it was mentioned if the flash drive is encrypted..? If not, you should also consider doing that and possibly using a software like 'BitDefender USB Immunizer' or 'Panda's USB Vaccine' as an added precaution. Flash drives are a bit like those plastic shopping baskets at the grocery store in that they can get really filthy when used by many hands, or in this case, plugged into multiple PC's. The gist of this being that it is all to easy for malware to be transferred from an infected machine running say, Windows and plopping it into a Linux hard disk where it can do little or no damage but can be transferred to another PC either directly or thru other means.

I am going to agree to disagree. Ubuntu is based on the concept of sudo,
which is a commandline app used as follows:

sudo whateverrootcommandyouwanttouse

Why this is a good idea is that only the root command you enter is executed
with root privileges, and nothing else. It allows you to avoid the trap
some OS'es (like some earlier Windows versions) had with assuming you were
ALWAYS an administrator and everything you do is at an administrative level.

(What's the rule on richtext? Italics would make that above so much easier
to use.)

OK, I can't say you're incorrect about sudo, but I still feel most strongly that one should reserve Administrative logins for Administrative functions and User logins for all else. Why then would the designers of Ubuntu et al, give options for standard user accounts if not for reasons of security? I can't imagine it would be for the sole purpose of making things more complicated for standard users (i.e. extra keystrokes). Indeed, if the standard user accounts are no more or less secure, then why not make all users administrators? I can't imagine this was done to slow things down in order to provide time for second guessing each action and ruminating over possible consequences.

I've tried italics in these postings, which is largely why I decided to use BOLD instead. Not sure if that works either. :)

This is an old argument and it largely comes down to preference, like Emacs
vs vim. It its an argument that can't be won, or lost. Sudo goes back to
unix as an admin tool. Ubuntu only made it fashionable.
When I switched to Ubuntu from other distros it took me a long time to like
sudo, but now the other seems strange. Not allowing root logons is a good
idea if you cater to newbies which is one reason why sudo works in Ubuntu.
Note that I did not say best.
You can use sudo su to stay as root for awhile.

No insult intended to anyone, but I have yet to be disappointed by
underestimating the ability of anyone to break virtually any software, newbs
notwithstanding. It just seems to me that sudo seems to limit the damage to
intentional at the minimum.